1. Field of the Invention
The present invention is directed generally to an exposure unit in a film changer, wherein the exposure unit has upper and lower platens which are movable in height relative to one another so that film may be introduced therebetween in one position of the platens and so that the platens press against the film in another position.
2. Description of the Related Art
The quality of a film exposure, and in particular of an x-ray exposure, is dependent on, among other things, how tightly the entire surface of the film presses against the upper platen and the lower platen, or against the reinforcing foil allocated to the platens, during exposure. The quality of the exposure, for example, deteriorates when the platens or the reinforcing foils are not pressed parallel against the film, such as x-ray film, or when air is present between the x-ray film and the reinforcing foils.
In some known exposure units, the upper platen is rigidly attached in the upper region of the exposure unit. The lower platen whose movement ensues, for example, via an eccentric cam that is secured to the exposure unit, is movable in height. In order to obtain parallel positioning of the platens of the exposure unit, the surfaces on which the upper platen rests must be first subject to extremely tight tolerance demands during manufacture. Secondly, the lower platen is adapted to the upper platen in that the lower platen is aligned with different thicknesses of shims. Such measures are extremely time consuming and, as a result, are very expensive.